My interests are in climate variability and change on timescales of seasons to millennia and in particular the causes of multiyear droughts around the world and how climate change will impact global hydroclimate. I analyze observations, proxy climate records and model simulations and also use idealized modeling to understand the basic climate dynamic processes in the atmosphere and ocean that generate global climate variability and change.

Some 40 million people depend on the Colorado River Basin for water but warmer weather from rising greenhouse gas levels and a growing population may signal water shortages ahead. In a new study in Nature Climate Change, climate modelers at Columbia University’s Lamont-Doherty Earth Observatory predict a 10 percent drop in the Colorado River’s flow in the next few decades, enough to disrupt longtime water-sharing agreements between farms and cities across the American Southwest.

We may think of the Pacific Northwest as rain-drenched, but new research led by scientists at the University of Pittsburgh shows that the region could be in for longer dry seasons, and is unlikely to see a period as wet as the 20th century any time soon.

Expanded irrigation has made it possible to feed the world’s growing billions—and it may also temporarily be counteracting the effects of climate change in some regions, say scientists in a new study. But some major groundwater aquifers, a source of irrigation water, are projected to dry up in coming decades from continuing overuse, and when they do, people may face the double whammy of food shortages and higher temperatures.

Some of the worst droughts to hit North Africa in the last 900 years have occurred recently—in the late 20th century—according to an analysis of tree rings that has provided the most lengthy and detailed climate record yet for this sub-tropical region on the Mediterranean.

A 2005-2007 dry spell in the southeastern United States destroyed billions of dollars of crops, drained municipal reservoirs and sparked legal wars among a half-dozen states—but the havoc came not from exceptional dryness but booming population and bad planning, says a new study.

Researchers have developed the first year-by-year record of rainfall in sub-Saharan West Africa for the past 3,000 years, and identified a daunting pattern: a 30-to-60-year cycle of serious droughts that last a decade or more, punctuated by killer megadroughts that last for centuries.

NEW YORK – Climate scientists using computer models to simulate the 1930s Dust Bowl on the U.S Great Plains have found that dust raised by farmers probably amplified and spread a natural drop in rainfall, turning an ordinary drying cycle into an agricultural collapse. The researchers say the study raises concern that current pressures on farmland from population growth and climate change could worsen current food crises by leading to similar events in other regions.

Dec 10, 2007--Scientists from Columbia University’s Lamont-Doherty Earth Observatory will report this week on vital topics including new evidence of the effects of climate change; technologies to confront it; studies of eastern U.S. earthquake risk; and previously unseen inner workings of the deep polar ice caps. The reports will be presented at the fall 2007 American Geophysical Union (AGU), the largest earth-sciences gathering in the world, Dec. 10-14 in San Francisco.

Researchers from the Lamont-Doherty Earth Observatory of The Earth Institute at Columbia University have used 835 annual tree-ring chronologies based on measurements from 20- to 30-thousand tree samples across the United States, Mexico, and parts of Canada to reconstruct a history of drought over the last 2005 years. The resulting drought reconstructions have been organized into a North American Drought Atlas CD-ROM, the first of its kind, which maps year-by-year occurrences of droughts.

Severe drought in western states in recent years may be linked to climate warming trends, according to new research, led by scientists from the Lamont-Doherty Earth Observatory of The Earth Institute at Columbia University, to be published in the journal Science. This research was supported by the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF).